For example, someone playing the QQQ's could be arbing and calculating the price they're willing to buy/sell and their system update it with each tick of the nasdaq e-mini. At one moment, it could be a penny (or fraction) inside the NBBO, and the next it could be a penny (or fraction) outside.

That would look like "flashing", yet be totally legitimate based on their valuation of the QQQ's at that instant.

It's too precise .It's seems more like a signal .
It does not happen often at the best bid but few levels below and few seconds later it actually goes to that precise level.
SethArb explaination is more like it, but I still think it might also be a signal.

It's too precise .It's seems more like a signal .
It does not happen often at the best bid but few levels below and few seconds later it actually goes to that precise level.
SethArb explaination is more like it, but I still think it might also be a signal.

More...

Signal? Paranoid.
.
.
.
.
Just pulling your chain. Lots of signals, and when you figure out what they mean, be sure to pm me.